An account of what he did at Brest is preserved in a manuscript copy of a report that he made to the commissioners. This report was published by Mrs. Sutcliffe in her book on the “Clermont” but it is so graphic that with Mrs. Sutcliffe’s consent it is reprinted in full exactly as Fulton wrote it:
Robert Fulton to the citizens Monge, La Place and Volney, members of the National Institute, and Commissioners appointed by the first Consul to promote the invention of Submarine Navigation—
Citizens, yesterday on my return from Brest I received your note, and will with pleasure communicate to you the result of my experiments, during the summer, also the mode which I conceive the most effectual for using my invention against the enemy. Before I left Paris I informed you that my plunging boat had many imperfections, natural to the first machine of so difficult a combination, added to this I found she had been much injured by the rust during the winter in consequence of having in many places used Iron bolts and arbours instead of copper or brass, the reperation of those defects and the difficulty of finding workmen consumed near two months. And although the machine remained still extremely imperfect yet she has answered to prove every necessary experiment In the most satisfactory manner.
On the 3d of thermidor I commenced my experiments by plunging to the depth of 5 then 10 then 15 and so on to 25 feet but not to a greater depth than 25 feet as I did not conceive the Machine Sufficiently Strong to bear the Pressure of a Greater column of water, At this depth I remained one hour with my three companions and two candles burning without experiancing the least inconvenience.